1. Field of the Invention
The present invention relates to a cleaning device for a copier, facsimile transceiver, printer or similar image forming equipment and, more particularly, to a cleaning device of the type scraping off a toner remaining on the surface of an image carrier made of photoconductor by having the ridge of the free end thereof pressed against the the image carrier.
2. Discussion of the Background
A cleaning device of the type described has a blade support mounted on an axis which is parallel to the surface of the image carrier and perpendicular to an intended direction of movement of the surface, and a cleaning blade affixed to the free end of the blade support such that the free end of the blade protrudes a predetermined amount from that of the blade support. The cleaning blade is pressed via the support member to have the free end thereof urged against the surface of the image carrier. In this condition, the end face of the cleaning blade stops and scrapes off a toner remaining on the image carrier. This type of cleaning device is disclosed in, for example, Japanese Patent Laid-Open Publication No. 156284/1990. This Laid-Open Publication includes an implementation for eliminating excessive wear of the surface of the image carrier, defective drive of the image carrier, defective cleaning occurring when the free end of the blade is entrained by the image carrier, etc. The implementation is such that the surface of the cleaning blade facing the image carrier and a line tangential to the surface of the image carrier at the point where the blade contacts the image carrier have an angle, or contact angle, of 9.5-14.5 degrees therebetween, while the blade is pressed against the image carrier by a force of 0.1-10 g/mm.
However, the above-mentioned contact angle and other factors of concern should not be set up when the surface of the image carrier is not moving relative to the cleaning blade for the following reasons. While a cleaning operation is under way, the free end of the cleaning blade is deformed by friction ascribable to the movement of the surface of the image carrier relative to the blade. As a result, the angle between the end face of the cleaning blade and the line tangential to the surface of the image carrier at the point of contact, i.e., the cleaning angle, changes. The cleaning angle is one of major factors that determine the ability of the cleaning device. The degree of such deformation of the cleaning blade before and after the movement of the surface of the image carrier depends on the Young's modulus E and thickness t of the blade, the distance l over which the blade protrudes from the blade support, etc.
Therefore, to achieve a desirable cleaning ability, it is necessary that the Young's module E, thickness t and protuberance l of the cleaning blade as well as other factors of concern be so selected as to set up an adequate cleaning angle during cleaning operation.